In a cellular radio communication system, total received power received at a base station includes background noise of the base station and a sum of received power of all user equipments in serving and non-serving cells.
The user equipments contribute to the total received power and consume the radio resources. In other words, the user equipments introduce uplink interference which comes from both intra-cell interference and inter-cell interference. The inter-cell interference, which is caused by user equipments in neighboring cells, is becoming an important factor which impacts uplink performance.
A relative measure of the uplink interference is rise over thermal (ROT), i.e. a ratio of the uplink interference to the background noise of the base station. Tolerable ROT of a cell depends on the desired coverage of the cell. The smaller the coverage of the cell, the higher the tolerable ROT. Radio resources that can be allocated in the cell may be determined based on comparison of a measured ROT and the tolerable ROT. In a case that the measured ROT is much lower than the tolerable ROT, more radio resources can be allocated in the cell, and vice versa.
User equipments severed by a serving cell may introduce serious ICI in neighboring cells, in a case that the serving cell has a high tolerable ROT and the neighboring cells have a low tolerable ROT and in a case that the user equipment is close to the neighboring cells.
In the worst case, the ICI is so serious that the user equipments in the serving cell blocks the neighboring cells. Consequently, no user equipments can be served by the neighboring cells. However, the neighboring cells with the low tolerable ROT are normally the ones with a large serving area. Blocking the neighboring cells with the low tolerable ROT is unacceptable because it cause large coverage holes.
It is still desirable to mitigate the ICI in view of the difference in the tolerable ROT of the serving cell and the neighboring cells so as to balance the serving cell and the neighboring cells for ensuring cell coverage and user experience.